1. Field of the Invention
This invention relates generally to a continually variable transmission (CVT) that is able to produce forward and reverse drive and to operate in a torque split mode.
2. Description of the Prior Art
CVT transmissions produce variable speed ratio required for a motor vehicle by changing the radial position at which a drive belt engages an input pulley and an output pulley. But CVT transmissions may have low mechanical efficiency and a limited range of drive ratio.
A need exist for a control technique or kinematic arrangement that extends the overdrive range of a CVT transmission, provides the reverse drive function required for a torque converter vehicle launch using a CVT, yet requires a minimum number of friction control elements, such as clutches and brakes.